Electronic vapor provision systems such as e-cigarettes generally contain a reservoir of liquid which is to be vaporized, for example, nicotine. When a user inhales on the device, a heater is activated to vaporize a small amount of liquid, which is then inhaled by the user through a mouthpiece. More particularly, such devices are usually provided with one or more air inlet holes located away from the mouthpiece. When a user sucks on the mouthpiece, air is drawn in through the inlet holes and past the vapor source, such as the heater supplied with nicotine or other liquid from a cartridge.
In some known devices, the user can exercise a certain degree of control over the air inflow into the device. Such control may be utilized, for example, to alter the draw resistance of the device. An electronic vapor provision system should provide a user with an airflow control mechanism that helps to achieve ease-of-use and reliability.